It is common to make housings, such as outlet boxes, in various sizes to accommodate varying numbers and sizes of electrical components such as electrical outlets, switches, dimmer units, etc. Perhaps the most common situation in which this need arises in is the case of wall switches. A box of one size is made to receive one switch and boxes of other sizes are made to receive two, three or even more switch units. The multiple-switch boxes are normally the same height as those made to receive one switch, but the width is approximately an integral multiple of the width of the single-switch size.
This multiplicity of sizes creates manufacturing and inventory problems for everyone concerned with such items, including the fabricator, distributors, retailers and builders, because they must be concerned about producing and stocking an inventory of units in each size to adequately serve a market in which needs vary with the seasons and with economic conditions.
It has been recognized that it would be desirable to be able to form boxes for various purposes in such a way that more than one could be joined together to enlarge the total capacity, and examples of such devices are found in the following U.S. patents.
U.S. Pat. No. 1,817,307 Haase et al;
U.S. Pat. No. 3,622,029 Ware;
U.S. Pat. No. 3,728.4701 Maier;
U.S. Pat. No. 3,840,140 Tisbo;
U.S. Pat. No. 4,202,457 Tansi.
However, these prior art devices exhibit deficiencies which have prevented them from being fully practical or commercially acceptable.